How to install freestyle stroke shader script to Blender 2.8
It won't work without a bit of reverse-engineering. The modules have different names, and they have a few Blender-specific calls.. Check out your [Blender installation directory]/scripts/freestyle/styles for Blender examples.. and the Blender Freestyle API. 

You've probably already been there, but the background reading makes for a good start, if you're trying to get your head round other people's code.